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Crabgrass (Digitaria spp.) is a summer annual weed that thrives in moist, warm soil, although in maturity it tolerates less moisture. It tends to infest lawns with problems, such as bare spots or those that are kept too short. Left alone, crabgrass and other weeds can completely choke out a lawn or take over bare ground. Mowing won’t rid the yard of these pesky plants because many of them propagate from rhizomes and seeds. Completely overhauling a weed-infested backyard is a lengthy project but reclaiming it provides great rewards.

Cut it Down to Size

Put the mower on its lowest setting and mow down all the crabgrass and weeds in the backyard. Use the bag on the mower so that it vacuums up the weed’s seeds instead of having them scattered, only to germinate and sprout a whole new mess. With the weeds and crabgrass cut down, you can now choose to use an herbicide to get rid of the roots or employ a more organic method of control.

Solarize

Solarization is a way to destroy weeds using the sun’s heat, so the best time to perform it is during the hottest time of the year. It is a lengthier process than using an herbicide, but it’s not toxic and it also kills certain soil-borne pathogens. The soil must be moist to a depth of 2 feet to retain heat, so water it slowly and deeply after mowing. Use clear plastic sheeting to cover the area, as close to the soil as possible, and anchor the sheeting with bricks or rocks to keep it from blowing away and to keep the air out and the heat in. Remove the plastic in six to eight weeks.

Herbicide

A quicker way to kill the crabgrass and weeds is to use a non-selective herbicide containing glyphosate. You’ll need to wear protective clothing, gloves, eyewear and a mask to guard against breathing the fumes. Follow all label instructions for mixing and using the product. A general rule of thumb, however, calls for 2 ounces of glyphosate to 1 gallon of water. This provides you with a 1.5 percent solution, which is best for crabgrass treatment. Load the water and the chemical into a handheld sprayer. If you’ll be using a pump-up or backpack sprayer, mix the glyphosate and water in a separate container and then pour it into the sprayer. Glyphosate will kill almost everything with which it comes into contact, so use care when spraying it around desirable ornamentals.

A Clean Slate

Wait at least one week after spraying to till and plant. If you plan on planting a lawn, you’ll need to till the soil. Till as deep as you like if you used glyphosate to kill the weeds. If you solarized the area, you’ll need to be a bit more careful with the tilling depth and not dig more than 2 inches deep. Any deeper and you may bring pathogens or weed seeds to the surface of the soil, notes the University of California's Integrated Pest Management Program.

About the Author

Based in the American Southwest, Bridget Kelly has been writing about gardening and real estate since 2005. Her articles have appeared at Trulia.com, SFGate.com, GardenGuides.com, RE/MAX.com, MarketLeader.com, RealEstate.com, USAToday.com and in "Chicago Agent" magazine, to name a few. She holds a Bachelor of Arts in English with a concentration in creative writing.